1. Field of the Invention
The invention relates to an optical coating equipment and an ultraviolet irradiative device, and in particular, to an ultraviolet irradiative device with covering boards which can adjust the irradiated area of an ultraviolet light source.
2. Description of the Related Art
FIG. 1 is a conventional optical coating equipment, comprising a film 1, a delivery device 2, a coater head 3, an oven 4, an ultraviolet irradiative device 5, and a cooling plate 6. The delivery device 2 comprises an unwinding machine 2a and a winding machine 2b. The film 1 is unwound by the unwinding machine 2a, and then the film 1 is coated with an optical liquid by the coater head 3. When the film 1 passes through the oven 4, an organic solvent of the optical liquid evaporates. The optical liquid is solidified by the ultraviolet irradiative device 5. Finally, the winding machine 2b winds the film 1 and formation of an optical film is complete.
The optical coating is a roll-to-roll coating method, thus the film 1 continuously passes through the oven 4 and the ultraviolet irradiative device 5 at the same velocity. Thus, the evaporation time of the organic solvent in the oven 4 and the irradiation time of the ultraviolet irradiative device will be changed simultaneously. To ameliorate this disadvantage, a conventional method, which changes the velocity of the unwinding machine 2a and the number of ovens, is provided. However, efficiency and capacity of the production are decreased by using this method. Another method, which adjusts the power of the ultraviolet light source by adjusting the distance between the film and the ultraviolet light source or a converter, is provided. Although the irradiative quantity is adjusted, the irradiative intensity of the ultraviolet light source is also changed. Thus, new variations occur.
Additionally, a great quantity of infrared rays are produced by the ultraviolet light source of the ultraviolet irradiative device 5, thus the surface temperature of the film 1 increases. Generally, a cooling plate 6 is disposed under the film 1 to cool the film 1. However, two opposite surface temperatures of the film 1 are different when passing through the ultraviolet irradiative device 5 and the cooling plate 6. Thus, the bottom of the film 1 is easily fogged.